Remark 4.2 In contrast with the case \(p=2\) ,
the composite homomorphism \(B_{2n+2} \rightarrow \operatorname{Sp}_{2n}({\mathbb {Z}}) \rightarrow \operatorname{Sp}_{2n}({\mathbb {F}}_p)\) 
is surjective for all prime numbers \(p > 2\)  (see [1]}).

